1. Field of the Invention
The present invention relates to a push-lock device which is attached to an electrical component such as audio-devices for vehicles wherein when being pushed inwardly, an operating shaft protruding from the electrical component is maintained at a locking position and when being repushed inwardly, the operating shaft is released from the locking state.
2. Description of the Related Art
Generally, a push-lock device is constituted of a case attached to an electrical component such as a rotary-type variable resistor and a rotary switch, a sliding body housed movably in the case and having a cam groove so-called a heart-shaped cam, an operating shaft having one end coupled to the sliding body and inserted into the electrical component, a return spring for biasing the sliding body in the direction of the operating shaft, and an operating pin having one end supported upon the case and the other end being traceable along the cam groove.
In such a push-lock device, when the operating shaft protruding from an electrical component is depressed against the biasing force of a return spring, the sliding body moves and approaches to the moving end thereof and the operating pin traces along the cam groove of the sliding body, thus being latched at a predetermined position of the cam groove. As a result, the sliding body is held in a locking state by way of the operating pin. Sequentially, when the operating shaft is depressed again, the operating pin is unlocked from the predetermined position of the cam groove, whereby the sliding body is released from the locking state. Since this step can house the operating shaft inside a panel, the beauty of mobile audio-apparatus or the like can be improved. Furthermore, a careless mistake that an operator inadvertently hits and catches on the operational shaft can be prevented by removing, if necessary, the protruding state of the operating shaft.
However, in the conventional push-lock device, when the operating shaft in a locking position is redepressed and then released, the operating shaft and the sliding body are returned quickly by the biasing force of the return spring. For that reason, there are problems in that a hit of the sliding body against the moving end produces an impact noise and the knob inserted in the end of the operating shaft comes out.